1. Field of the Invention
The present invention relates to technology for clearing a jammed paper in an image forming apparatus.
2. Description of the Related Art
For example, Japanese Patent Application Laid-open No. 2000-062985 discloses an image forming apparatus that includes a plurality of paper feeding trays that has a series of paper conveying paths extending to the apparatus body, a locking mechanism that locks each of the paper feeding trays, and a control unit that controls locking operation of the locking mechanism. Each of the paper feeding trays is provided with a paper feeding unit that feeds paper to the apparatus body, and an operation detecting unit that detects the start of paper feeding by the paper feeding unit. When any one of the operation detecting units detects the start of paper feeding by a paper feeding unit, the locking mechanism locks a paper feeding tray from which paper feeding is started, and all other paper feeding trays arranged on the upper position than the paper feeding tray. When a paper feeding tray is locked, it cannot be pulled out of the apparatus body. When a paper jam is detected, a lock set by the locking mechanism is released so as to permit pulling out of a paper feeding tray from the apparatus body.
By locking paper feeding trays with the locking mechanism, it is possible to prevent a trouble, for example, jamming caused by breaking of a paper conveying path resulting from pulling out (withdrawing) a paper feeding tray in the paper conveying path. However, a possibility has not been considered that a sheet of paper inside the apparatus is stopped on the way between a paper feeding tray and the apparatus body when jamming occurs and the apparatus halts.
If a sheet of paper is stopped on the way between a paper feeding tray and the apparatus body, a tray lock is released. As a result, if a user pulls out the paper feeding tray in a fluster while the sheet of paper is stopped, the sheet of paper inside the apparatus is broken, and a residual piece of paper may be disadvantageously left inside the apparatus.